Integrated circuits (“IC”), which generally refer to electronic circuits formed on a silicon or other semiconductor substrate, have widespread application in modern electronic systems. An IC chip may contain circuit devices, such as transistors, and electrical interconnects to electrically couple the circuit devices. An outer surface of the IC chip may also contain conductive pads for providing electrical coupling of the chip to external devices, such as voltage sources and control circuits. Traditionally, electrical connection between the transistors in the semiconductive substrate and the conductive pads is accomplished through the use of multiple conductive layers that are formed over the semiconducting substrate of the integrated circuit chip but below an insulative layer that supports the conductive pads (an aperture in the insulative layer can provide electrical coupling of the contact pad to the uppermost conductive layer). For example, an integrated circuit chip may have metal lines and vias that electrically couple the source and drain regions of the transistors to the conducting pads of the integrated circuit chip.
Voltage regulators, such as DC to DC converters, are used to provide stable voltage sources for electronic systems. Switching voltage regulators are known to be an efficient type of DC to DC converter. Such voltage regulators typically include a power switch to generate a rectangular-wave voltage that is filtered to provide the output DC voltage.
Conventionally, the power switch was fabricated as an integrated circuit chip with wire bond packaging. More recently, the power switch has been fabricated as an integrated circuit chip with flip-chip packaging (in which solder bumps are placed on the top surface of the chip, and the chip is mounted upside down with the solder bumps connected directly to a printed circuit board, interposer, or to a package).